The present invention relates generally to the art of electric motors. More particularly, the invention relates to an improved frame for the housing of an electric motor.
The frame of an electric motor houses the stator and the rotor. In a conventional frame, a separate conduit box is typically located on the exterior of the frame for providing access to the motor's various electrical leads. The separate conduit box adds both cost and volume to the motor.
Operation of an electric motor generates heat that must be removed. Conventional motors often provide cooling by forcing air through or over the motor. At least two configurations for such forced air cooling are known. One cooling configuration is frequently used in motors in which the housing interior is closed off from the ambient air. The other cooling configuration is often used in motors in which the housing interior is open to ambient air.
In a typical closed motor configuration, the frame of the motor housing is provided with a plurality of air channels. Each air channel extends axially along the frame. A cowling having vent openings defined therein is mounted to one end of the frame. A shaft-mounted fan, or separately-powered in-line blower, is located in the cowling to force air through the air channels. Heat is dissipated to the forced air by conduction through the frame.
In the open cooling configuration, a mounting bracket may be attached to the end of the motor frame. The bracket is configured to support a blower fan powered by a separate motor. Operation of the fan forces air into the frame of the motor housing. A small gap exists between the rotor and the stator, and some cooling air can pass through this gap to circulate around the opposite end of the stator/rotor assembly, i.e., the end that is farther from the fan. In addition, the rotor may be provided with elongated passages extending axially therethrough to permit transfer of some forced air from the end of the rotor that is nearer to the fan, to the end of the rotor that is farther from the fan. Air may also be forced through axial channels in the frame since they are internal to the motor in this cooling arrangement.